"When Homer announces he would sell his soul for a donut, the Devil, disguised as Ned Flanders, shows up to take him up on the offer. Second Act, while ridings to school, Bart believe he sees a malevolent gremlin on the side of the bus. And final act, Mr. Burns is Dracula, in a spoof of Francis Ford Coppola's vampire film."

Bart is seen walking around a room with paintings in light of Rod Serling's Night Gallery and tries to introduce the show but Marge and Maggie interrupt telling Bart to tell the viewers the show is scary but Bart ignores and we watch the first part.

Homer falls asleep at work, dreaming of donuts. When he wakes up to get one to eat, he finds out from Lenny and Carl that the remaining donuts have already been eaten. Homer then declares that he'd sell his soul for a doughnut, causing the Devil (in the form of Ned Flanders) to appear. After signing a contract, Homer is given his doughnut, with the provision that as soon as it's finished, the Devil will own his soul. However, Homer finds a loophole: if he doesn't finish the doughnut, he's safe. Homer openly mocks this loophole, to which the Devil promises that he will go to Hell eventually. One evening, Homer goes down to the kitchen, and without realizing it, eats the last of the doughnut. As expected, the Devil comes to take Homer's soul, but Lisa asks him to hold a trial, which the Devil agrees to. However, Homer must spend the day in Hell being severely tortured. Aside from being chopped into pieces, a demon in the Ironic Punishment Division laughingly plans to feed Homer all the donuts in the world (this plan backfires when Homer gleefully keeps eating, much to the confusion of the demon). Back on Earth, Marge already has the trial area set up and hires Lionel Hutz to defend Homer.

The Devil and Hutz barter on specific terms before the trial begins: The Devil agrees to Hutz's request for bathroom breaks, and Hutz agrees that the Devil can choose the jury. The Devil's jury includes Benedict Arnold, Lizzie Borden, Richard Nixon (still alive at the time), John Wilkes Booth, Blackbeard the Pirate, John Dillinger, and the 1976 Philadelphia Flyers. The Devil gives the evidence of the contract Homer signed, pledging his soul for a donut. Lionel Hutz counters with the definition of a contract according to the dictionary, stating it as something that is unbreakable. Realizing that he's put his foot in his mouth, Hutz asks to be excused to the bathroom. When he doesn't return immediately, Marge finds the bathroom window open and Hutz long gone.

As the judge prepares to sentence Homer, Marge shows the jury a photo album showing their wedding day, where Homer's eating of the whole wedding cake sent them to the emergency room. On the back of a photograph, it is revealed that in a statement of love to Marge, Homer pledged his soul to her. This causes the jury to declare Homer's deal with the Devil to be revoked. However, the Devil is not willing to let Homer best him. With a zap of his power, the Devil turns Homer's head into a doughnut.

The next morning, Homer can't stop eating parts of his head. As he decides to go to work, Lisa cautions him to stay home...because standing outside the house are the Springfield Police Department, waiting to rip apart his doughnut-made head and enjoy it with their morning coffee.

Bart has a nightmare where the bus crashes and wakes up very paranoid. Bart and Lisa then get on the bus on one rainy morning with Principal Skinner on the bus. Lisa informs everyone that Bart is acting paranoid, and asks that they act nice to him, causing everyone to laugh at him instead. In the middle of the ride, Bart hears tapping on the window, but it is only Groundskeeper Willie, who says he had to kill his mule and needs a ride. Bart's nightmare then comes true when a gremlin is attacking the bus Bart keeps trying to warn everyone but every time anyone but Bart looks the gremlin hides and it even causes Otto to destroy Hans Moleman's AMC Gremlin. Bart then becomes very annoying to the people on the bus and it causes Skinner to close the window, and forces Bart to sit next to Üter the German foreign exchange student. Bart eventually gets the emergency flares and throws one at the gremlin, knocking it off the bus, only to be picked up by Ned. After arriving safely to the school, everyone notices severe damage done to the outside of the bus. Bart stopped the gremlin from destroying the bus, but with no one as an alibi, he is declared insane for his behavior and is sent to the New Bedlam Insane Asylum for the rest of his life. On the way, Bart begins to relax at the thought of never having to worry about the gremlin. At that moment, the gremlin shows up at ambulance's back window and shows Bart Ned Flanders severed head, causing him to scream uncontrollably.

They originally had a story to go with the famous Dogs playing Poker picture (Homer is frightened at this painting), but Bart said it was too twisted and scary to show on TV. So they had to put a random story about vampires together.

The Simpsons are watching TV to find out a vampire has attacked and this convinces Lisa vampires are real. The Simpsons are then invited to Mr. Burns's mansion for a midnight dinner in Pennsylvania. There it is obvious that Burns is a vampire but no one believes Lisa. She and Bart find Mr. Burns's secret lair which can be accessed by a staircase that has a lever which doubles as a fun slide and Bart (while fleeing from a horde of vampires) says "I shouldn't... But when am I going to be back here?" is turned into a vampire after pulling the lever. The Simpsons are then worried that Bart could get worse and The Simpsons have to kill the head vampire. Homer then places a stick in Burns' heart and kills him but gets fired in the process. The Simpsons are then eating dinner and Lisa finds out that her whole family is vampires and Lisa mistakingly killed Burns but she should've killed Marge, the real head vampire ("I do have a life outside of this house, you know."). The vampire family surrounds and corners a terrified Lisa...

The episode finished 17th in the ratings for the week of It originally aired, with a Nielsen rating of 14.5. It was the highest-rated show on the Fox network that week.

Since airing, the episode has received positive reviews from TV critics and fans alike. The authors of the book I Can't Believe It's a Bigger and Better Updated Unofficial Simpsons Guide said it was "probably the best" Treehouse of Horror episode in the show. It has since been given an A grade by many online DVD critics and Kim Nowacki named it his favourite Treehouse of Horror episode.